The invention concerns a spark-generating piezoelectric igniter of the percussion and push-button trigger type.
Igniter devices or piezoelectric igniter devices are well known and are used in particular to generate sparks to inflame certain gaseous mixtures. Because such devices are widely known they need not be described in detail.
A device of this type is described in the French Pat. No. 1 554 247, wherein the percussion member consists of a metal rod and a piezoelectric element rigidly connected to it, said element when acted upon by an energy storing means in the actuation of the device impacts a fixed anvil causing a spark to fly. However such a device is rather complex, comprises many parts and most of all requires, on account of the necessary displacement of the piezoelectric element, that the high voltage terminal make contact with the anvil and that it not be permanently connected to the piezoelectric element itself. As a result, the amount of generated electrical energy can only be delivered in an uncertain manner to the spark gap, there being no assurance of proper contact between the percussion element and the anvil following the impact (also see U.S. Pat. No. 3,751,690 and German Offenlegungsschrift No. 2 853 326).
As a rule the push-button and percussion type piezoelectric igniters marketed to date consist essentially of:
a percussion mass capable of elastic displacement and provided with two diametrically opposite stubs displaceable on an incline made for that purpose on the push-button body;
a spring resting against the stubs and the inside of the push-button body respectively;
a plastic, insulating cylindrical casing, conventional for this application, which is both shock and temperature resistant, and of which one end receives the push-button assembly and the percussion mass, and the other end of which receives the conventional impact assembly comprising essentially the striker, the piezoelectric crystal, the anvil, the connection and the lock washer.
Briefly, when the push-button is depressed, the spring is compressed, whereupon the stubs move on the inclines until at the end of their travel the percussion mass is abruptly released so that, under the influence of said spring, it impacts the impact assembly and thus generates the spark. Thereupon the mass is returned to its initial position by a suitable return spring.
Even though these devices are in fairly widespread use, they still suffer from the substantial drawback that they are tedious to manufacture and assemble and their fabrication is not easily automated.